1. Field of the Invention
The present invention relates to paper making. In particular, it relates to a multi-component system for improving wet-end chemistry in paper making.
2. Brief Description of the Prior Art
In order to try to reduce the cost of paper and modify certain paper properties various expedients have been tried. Among these have been attempts to replace cellulosic fibers by filler materials such as kaolin clays. It has, however, proved to be difficult to maintain satisfactory quality, especially as the ratio of filler to fiber is increased.
Currently, many paper makers attempt to maximize filler and pulp fines retention by addition of a high molecular weight water soluble polymer, such as a derivatized polyacrylamide in an amount of from 0.3 to 1.5 lbs per ton of paper produced. The derivatized polyacrylamide used may be cationic or anionic in nature and in general it has been found that the higher the molecular weight of the material used, the greater has been the retention. On the other hand, as the molecular weight of the polyacrylamide increases, sheet formation deteriorates. Similarly, as the amount of polyacrylamide is increased, fines retention improves and sheet formation deteriorates.
A further problem confronted by paper makers is the removal of water from the furnish slurry when this is passed from the headbox of a paper making machine on to the moving wire belt on which paper sheet forms. Initially, water simply drains through the wire belt. As the belt progresses away from the headbox, the furnish slurry, from which the paper is forming, is subjected to additional drainage techniques such as vacuum assisted drainage. After this, the paper now has sufficient structural integrity to be removed from the wire belt and passed over heated rollers which lowers the moisture content even further to produce the finished product. The greater the amount of moisture that drains off on the initial section, namely the wire belt, the less is the cost of subsequent drying operations. Such early removal of water can be assisted by the presence of suitable drainage aids in the furnish. Low to intermediate molecular weight cationic synthetic polymers such as those based on polyacrylamide, polyethylene imine, polymers produced from dimethylamine and epichlorohydrin and polydiallyldimethyl ammonium chloride are examples of drainage aids currently in use.
Binder compositions comprising acrylic polymers are described, for example, in U.S. Pat. No. 4,298,513 (Distler et al).
U.S. Pat. No. 2,616,818 (Azodosa) describes an acrylamide-based paper coating composition.
U.S. Pat. No. 3,483,077 (Aldrich) describes the use of cationic thermosetting resins together with clays in paper making.
U.S. Pat. No. 2,795,545 (Gluesenkamp) describes the use in paper making of various clays such as bentonite in conjunction with polycations obtained by polymerization of monolefin compounds such as polydimethylaminoethyl methacrylate derivatives, polyvinylbutylpyridinium bromide, poly-2-methyl-5-vinyl pyridine and quaternary salts of styrene/methylvinylpyridine copolymers.
U.S. Pat. No. 4,305,781 (Langley et al) describes an improvement to furnish drainage rates using bentonite and high molecular weight substantially non-ionic polymers.
U.S. Pat. Nos. 3,697,370 (Nagy) and 3,732,173 (Nagy) disclose methylamine-epichlorohydrin polymers and their use in the manufacture of dry strength paper.
U.S. Pat. No. 3,288,770 (Butler) discloses polydiallyldimethylammonium chloride and methods of making it. The polymers may be used as wet strength improvement agents for papers.
U.S. Pat. No. 3,738,945 (Panzer et al) describes polyquaternary polymers derived from an epihalohydrin and a secondary amine i.e., dimethylamine. The main use of the polymers is as flocculants.
U.S. Pat. No. 2,884,058 (Schuller et al) features a copolymer of acrylamide and diallyldimethylammonium chloride and its use in paper making.
U.S. Pat. No. 4,432,834 (Whitfield et al) discloses a composition for addition to cellulosic fibers prior to felting them into a sheet comprising as component (a) a monomeric water soluble diallyl dimethyl ammonium halide or homopolymer thereof or mixtures thereof and as component (b) a water dispersible complex fatty amido compound, the proportion of (a) and (b) being sufficient to enhance softness of the dried sheet while increasing or not substantially reducing absorbency of water and tensile strength.
U.S. Pat. No. 4,171,417 (Dixon) teaches copolymers of dialkyl diallyl ammonium chloride and their use for making electroconductive paper.
U.S. Pat. No. 4,753,710 (Langley) teaches a process of adding a high molecular weight cationic polymer to a paper furnish followed by high shear and then subsequently adding bentonite to improve retention, drainage, drying, and formation. Also F167736 and W086/05826 discuss the use of cationic polymeric materials with colloidal silica.
U.S. Pat. No. 4,749,444 (Lorz) teaches that good printing quality paper can be made when three components are added to the paper stock for improved drainage and retention. These three components are water swellable clay referred to as a bentonite, within which definition other clays, including hectorite are apparently comprised, a low molecular weight, high charge density, cationic polymer and a high molecular weight derivatized polyacrylamide or polymethacrylamide.
U.S. Pat. No. 3,052,595 teaches the use of polyacrylamide and bentonite as a drainage and retention aid with high shear after the addition of the polyacrylamide.
U.S. Pat. No. 4,097,427 (Aitken et al) features the cationization of starch with polymers such as dimethylamine-epichlorohydrin and polydiallyldimethylammonium chloride. U.S. Pat. No. 4,146,515 (Buikema et al) has similar teachings.
U.S. Pat. No. 3,772,076 (Keim) describes reaction products of epihalohydrin and polymers of diallylamine and their use as wet strength agents for paper.
U.S. Pat. No. 3,520,774 (Roth) relates to a epichlorohydrinpolyethyleneimine reaction product and its use as a wet strength additive for paper.
U.S. Pat. No. 4,129,528 (Petrovich) teaches polyamine-epihalohydrin resinous reaction products and their use as wet and dry strength additives for paper.
U.S. Pat. No. 4,330,365 (Tessler) describes the use of cationic polymers wherein poly (n-N'-methyl bisacrylamide coamine) is grafted onto starch as a replacement for starch in paper making, for example, a pigment retention aid.
U.S. Pat. No. 4,198,269 (Evani) describes the use of cationic polyethers preferably having molecular weights in the range 10,000 to 60,000 as wet or dry strength enhancers for paper.
U.S. Pat. No. 3,930,877 (Aitken) describes the use of an epichlorohydrin dimethylamine condensate as a cationic additive for starch in paper making to assist in improving burst strength and pigment retention.
U.S. Pat. No. 3,278,474 (Nixon et al) describes the use of copolymers of unsaturated aldehydes and quaternary ammonium compounds to improve wet strength and abrasion resistance of paper.
U.S. Pat. No. 4,824,523 (Wagberg et al) uses a mixture of anionic and cationic polymers as additives to starch to improve the retention and dry strength properties of paper. The cationic polymers used are chosen from a wide variety of types including polyacrylamides modified by reaction with formaldehyde and dimethylamine, polydiallyldialkyl ammonium halides, cationic amido amines and polymers by polymerization of N-(dialkyl aminoalkyl) acrylamide monomers.
U.S. Pat. No. 4,818,341 (Degan) suggest use of a cationic polymer comprises copolymerized units of diallyldimethyl ammonium chloride and N-vinylamine or an N-vinyl imidazoline as a dry strength enhancer for paper and as an aid to dewatering of paper stock in sheet formation.
U.S. Pat. No. 4,785,055 (Dester et al) describes the use of the reaction product of an acidified polyacrylamide and a halide or halogen to produce a polymer that is useful as a wet strength enhancer in paper making.
U.S. Pat. No. 4,722,964 (Chan et al) describes improved cationic wet strength resins prepared from an epichlorohydrin ammonia reaction product and polyalkyleneamine amide and epichlorohydrin.
U.S. Pat. No. 4,711,727 (Matthews) describe the use of synthetic hectorite in an alkaline medium together with cationic and amphoteric electrolytes such as polyamines and dimethyldiallyl ammonium chloride for use as slurry stabilizing agents and flocculants in the treatment of sewage and in paper making.
Commonly, assigned copending application Ser. No. 07/211,550, filed on Jun. 24, 1988, (and its corresponding International Application published as WO 89/12661 on Dec. 28, 1989) the contents of which are herein incorporated by reference, describe the use of cationic starch together with hectorite in paper making. It contains a discussion of prior use of starch materials in binders for use in paper making.